Development of the arterial pattern in the upper limb of staged human embryos: normal development and anatomic variations

Abstract

A total of 112 human embryos (224 upper limbs) between stages 12 and 23 of development were examined. It was observed that formation of the arterial system in the upper limb takes place as a dual process. An initial capillary plexus appears from the dorsal aorta during stage 12 and develops at the same rate as the limb. At stage 13, the capillary plexus begins a maturation process involving the enlargement and differentiation of selected parts. This remodelling process starts in the aorta and continues in a proximal to distal sequence. By stage 15 the differentiation has reached the subclavian and axillary arteries, by stage 17 it has reached the brachial artery as far as the elbow, by stage 18 it has reached the forearm arteries except for the distal part of the radial, and finally by stage 21 the whole arterial pattern is present in its definitive morphology. This differentiation process parallels the development of the skeletal system chronologically. A number of arterial variations were observed, and classified as follows : superficial brachial (7n7 %), accessory brachial (0n6 %), brachioradial (14 %), superficial brachioulnar (4n7 %), superficial brachioulnoradial (0n7%), palmar pattern of the median (18n7 %) and superficial brachiomedian (0n7 %) arteries. They were observed in embryos belonging to stages 17-23 and were not related to a specific stage of development. Statistical comparison with the rates of variations reported in adults did not show significant differences. It is suggested that the variations arise through the persistence, enlargement and differentiation of parts of the initial network which would normally remain as capillaries or even regress.

An anatomical study of variations in termination of brachial artery: embryological basis and clinical implication

“…Another study has reported an anastomosis joining the brachial and brachioradial artery at the elbow in 3 of the 21 cases (14±3%) which is a higher incidence when compared to the present study [20].…”

Unusual ending of the second dorsal metacarpal artery as proper palmar digital arteries

“…Adachi [1] and Libersa et al [4] mention the 2DMA as source of PPDA; Edwards [15] relates this origin could be possible due existing anastomoses at the second web space, but in his series of specimens, he did not find it. Coleman and Anson [2] described its presence limited to the first and second digital web spaces.…”

Anomalous origin of the deep brachial artery (profunda brachii) observed in bilateral arms: case report

“…Variations in the branching patterns of the major arterial trunks have been reported with an incidence of over 20% in human adult limbs 7 . Despite this, several variations in its origin and in the course of the DBA, like other vessels of the upper limb, could be considered.…”

“…From this axial artery, which represents the axillary, brachial, and anterior interosseous, the forearm arteries appear successively. The axillary and brachial arteries begin their development at stages 16 and 17 successively and, therefore, anatomical variations including these vessels may have originated at this time 6,7 . In 55% of the cases 1,2 , the deep brachial artery (DBA) is the larger branch issued from the brachial artery (BA), and it leaves near the bottom edge of the teres major muscle to penetrate above the medial intermuscular septum on the lower triangular axillary space together with a radial nerve (RN) 8,9 .…”